- What is the comparative clinical effectiveness of vaccines administered using a needleless injector versus a needle syringe for individuals of all ages?
Fourteen randomized controlled trials (RCTs) regarding the comparative clinical effectiveness of vaccines administered using a needleless injector versus a needle syringe (N-S) were identified in this review. Five RCTs were for influenza vaccine, four for inactivated polio vaccine (IPV), two for measles, mumps and rubella (MMR) vaccination, one for the diphtheriatetanuspertussis, hepatitis B, and hemophilus influenza type B (DTP-HB-Hib) vaccine, one for human papillomavirus vaccination (HPV) and one for Bacille Calmette-Guérin (BCG) vaccination. Four needle-free jet injectors (NFJIs) used in the included trials are PharmaJet Injector, Med-Jet H4 injector, Biojector and LectraJet injector. For influenza vaccine: the findings observed in five RCTs indicated that influenza vaccine administered by NFJI, intradermally achieved similar immune response (e.g., seroconversion, seroprotection, antibody titer) compared with that administered by traditional N-S, intramuscularly. No evidence of a dose-sparing strategy for influenza vaccine using NFJI was identified.For IPV vaccine: the findings reported in four RCTs showed that compared with conventional full dose IPV (i.e., 0.5 ml) given by N-S, intramuscularly, a fractional dose of IPV (i.e. 0.1 ml or 1/5 of full dose), given by NFJI, intradermally demonstrated a similar seroconversion rate (both initial and boosting response), but lower antibody titer.The findings from two RCTs for MMR vaccination indicated that there was no statistically significant difference observed between NFJI, subcutaneously and N-S, subcutaneously in terms of immune response (e.g., seroconversion rate, antibody titer). For DTP-HB-Hib, HPV and BCG vaccine, the immune response (e.g., seroconversion rate, or seroprotection rate/ antibody titer or T-cell [CD4/CD8] response) introduced by NFJI were also similar to that observed in the N-S group. Regardless of the type of vaccine, or type of NFJI, numerically more unsolicited and solicited local adverse reactions (e.g., redness, swelling, induration and infiltration) were observed with NFJIs than with traditional N-S injection. However, the frequency of unsolicited and solicited systemic AEs (e.g., fever, headache, muscles aches, tiredness, nausea) were numerically lower in NFJI, intradermal injection group compared with N-S intramuscular injection group. In conclusion, the vaccines administered by NFJI were reported to be as immunogenic as that by N-S. However, more local injection reaction, but fewer systemic adverse events associated with NFJI were also reported. Despite some limitations of the study designs, the comparative effectiveness and safety profile of vaccines (e.g., influenza, IPV or MMR) administered by NFJI and N-S were consistent regardless the type of vaccine and the type of NFJIs. Future studies assessing NFJI as a dosesparing strategy comparing with conventional N-S are needed, especially for the influenza vaccine.